The survival time of sperm in the female reproductive tract after ejaculation into the vagina is normally less than 3 days, however, some people can survive for up to 5 days. If you want to have children, you can have intercourse 3 days before ovulation and you may get pregnant. The egg is viable for 24 hours and can last up to 48 hours. You can schedule intercourse according to the survival time of the sperm and egg and you may get pregnant. However, ovulation is not very constant in women and may occur unexpectedly due to environmental influences and moods. If there is no requirement for fertility, it is important to take effective contraceptive measures to avoid unwanted pregnancy, no matter when you have sex.